The live demonstration of Retopoflow 2 is not in the "past live streams" section yet. Why?
It took a little extra time to archive, and it's up now: https://cgcookie.com/live_streams/live-demo-of-retopoflow-2-0-with-jonathan-williamson
Houdini has Retopoflow-like functionality. It comes in the form of a node called "Topobuild".